In the anime

Latias sight-sharing with Latios while in Soul Dew form after its sacrifice

In the anime, it appeared in the movie Pokémon Heroes, in which it is used to guard Johto's Alto Mare. It was given to an old couple in Alto Mare long ago after Latios and Latias saved the city. The Team Rocket duo Annie and Oakley were looking for Soul Dew as well as the two legendary guardians of the city, Latios and Latias. If it is attached to the Defense Mechanism of Alto Mare (DMA), anyone using the device can drown the city in water, block all exits in the city and awaken the Fossil Pokémon, Kabutops and Aerodactyl. It is implied that this Soul Dew contains the soul of a deceased Latios.